Generally, a power storage device such as a secondary battery includes, as main components, a positive electrode, a negative electrode, and an electrolytic solution. In the electrolytic solution, an appropriate electrolyte is added in an appropriate concentration range. For example, in an electrolytic solution of a lithium ion secondary battery, a lithium salt such as LiClO4, LiAsF6, LiBF4, and LiB(C2O4)2 is commonly added as an electrolyte, and the concentration of the lithium salt in the electrolytic solution is set at about 1 mol/L.
In an organic solvent to be used in an electrolytic solution, a cyclic carbonate such as ethylene carbonate or propylene carbonate is generally mixed by not less than about 30 volt, in order to suitably dissolve an electrolyte.
Actually, Patent Literature 1 discloses a lithium ion secondary battery using an electrolytic solution that uses a mixed organic solvent containing ethylene carbonate by 33 vol % and that contains LiPF6 at a concentration of 1 mol/L. Furthermore, Patent Literature 2 discloses a lithium ion secondary battery using an electrolytic solution that uses a mixed organic solvent containing ethylene carbonate and propylene carbonate by 50 wt % and that contains LiPF6 at a concentration of 1.1 mol/L.
In addition, for the purpose of improving performance of batteries, studies are actively conducted for various additives to be added to an electrolytic solution containing a lithium salt.
For example, the above described Patent Literature 2 describes an electrolytic solution obtained by adding a small amount of a specific additive to a mixture that uses a mixed organic solvent containing ethylene carbonate and propylene carbonate at 50 wt % and that contains LiPF6 at a concentration of 1.1 mol/L. Patent Literature 2 discloses a lithium ion secondary battery using this electrolytic solution. Patent Literature 3 describes an electrolytic solution obtained by adding a small amount of a specific additive to a mixture containing LiPF6 at a concentration of 1 mol/L, and discloses a lithium ion secondary battery using this electrolytic solution. Furthermore, Patent Literature 4 also describes an electrolytic solution obtained by adding a small amount of phenyl glycidyl ether to a mixture containing LiPF6 at a concentration of 1 mol/L, and discloses a lithium ion secondary battery using this electrolytic solution.